עַל־כֵּ֡ן לֹֽא־יֹאכְל֨וּ בְנֵֽי־יִשְׂרָאֵ֜ל אֶת־גִּ֣יד הַנָּשֶׁ֗ה אֲשֶׁר֙ עַל־כַּ֣ף הַיָּרֵ֔ךְ עַ֖ד הַיּ֣וֹם הַזֶּ֑ה כִּ֤י נָגַע֙ בְּכַף־יֶ֣רֶךְ יַעֲקֹ֔ב בְּגִ֖יד הַנָּשֶֽׁה׃
Therefore the children of Yisrael do not eat the sciatic nerve that is on the hollow of the thigh, to this day, because he touched the hollow of Yaakov’s thigh on the sciatic nerve.
Torah Temimah points to Chullin 92b–93a.
תניא, רבי יהודה אומר: אינו נוהג אלא באחת, וטעם הדבר מפורש בברייתא.
It was taught: Rabbi Yehudah says: It applies only to one [thigh]. The reason is explained in the baraita.
Discussion of whether the prohibition applies to both thighs or only one.
Derash on the scope (Bavli).
According to Rabbi Yehudah the prohibition of the sciatic nerve applies to only one thigh.